1. Field of the Invention
The present invention relates to an electric storage element and a production method thereof.
2. Description of the Related Art
JP 2009-087727 A and JP 2009-087728 A each disclose a conventional battery configured such that each of a body and a distal end of a shaft of an external terminal is sequentially inserted into a through hole provided in a cover and a shaft through hole provided in an insulator with a gasket being interposed therebetween, and is then inserted into a shaft through hole provided in a first plate, and thereafter the distal end of the shaft is caulked, so that the cover, the insulator, and the first plate are held and integrated by the external terminal.
Furthermore, JP 2009-087693 A discloses a configuration in which a rivet portion of a rivet is caulked so as to press a projecting contact body of a current collector, and then the rivet portion and the current collector are welded by laser beams to form a welded portion.
However, in the configuration disclosed in JP 2009-087727 A and JP 2009-087728 A, the cover, the insulator, and the first plate are simply held and integrated by the external terminal. In addition, the gasket and the insulator are essentially provided in order to keep air tightness in the battery. Such a configuration leads to increase of the number of components and complicated production steps, thereby resulting in increase of production costs. JP 2009-087693 A merely refers to a feature in the configuration, that the rivet portion and the current collector are welded by laser beams, and the object thereof is to simply achieve a rigid fixed state. Furthermore, JP 2009-087693 A neither describes nor suggests air tightness.